The sensitivity of plants to heavy metals depends on an interrelated network of
physiological and molecular mechanisms such as (i) uptake and accumulation of metals
through binding to extracellular exudates and cell wall constituents; (ii) efflux of heavy
metals from cytoplasm to extranuclear compartments including vacuoles; (iii) complexation
of heavy metal ions inside the cell by various substances, for example, organic acids, amino
acids, phytochelatins, and metallothioneins; (iv) accumulation of osmolytes and
osmoprotectants and induction of antioxidative enzymes (v) activation or modification of
plant metabolism to allow adequate functioning of metabolic pathways and rapid repair of
damaged cell structures